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Discussion Starter · #1 ·
Three years ago I bought a used 2013 Lyrik Dual Position Air (26" FWIW). I did a full rebuild as soon as I got it, and again last year, and for the most part it works and feels great.

There is just one problem: I have seldom ever gotten more than 140mm travel and have never gotten past 145mm. This is even with the air pressure absurdly low and some botched jumps landed front heavy. It almost does not matter how much sag I run, it just seems to hit a wall around 140mm. Thing is, it still feels great. Its basically a really good 140mm fork. But I really want to know what is going on with that last 20mm. There are no volume tokens in this fork to take out.

So a few days ago I decided to get to the bottom (out) of the this, and determine if the issue was too small a volume in the air spring, hydrolocking in the damper, or pressure building in the lowers. See here for an entertaining/embarrassing account of the damper side test :oops:

What I found was that it is the air spring, but what is happening does not totally make sense to me, and I am wondering if something in the DPA assembly/design is the issue.

1- When I depressurize the fork to 0 psi, then push down on the bars with my weight, it is still pretty stiff at the end of the travel, and I don't get the last 10mm. Any other fork or shock I've had was very easy to push to the bottom when I let all the air out, so I don' think it is simply an issue of the main air chamber lacking volume unless it is REALLY small, as in it goes to near zero volume at full travel. It would really surprise me if they designed a fork like that.

2- I then pull the top cap off (along with the shaft that goes into the head of the main air piston) I can easily bottom the fork at 160mm. So the issue is NOT a bottom out bumper.

3- Then I put the topcap/shaft back in (without adding air) and now was able to easily bottom it..... this has me confused.

Because I get different results in step 1 and 3 (where in both cases I get a 0 psi reading with the fork extended), it is making me wonder if there is air getting trapped somewhere in the DPA assembly once I inflate. I am a bit in the dark as to what is inside the topcap and the shaft attached to it, as well as what is inside the main piston that the shaft inserts into. In other words, just how the DPA works is a bit of a black box to me. I am wondering if over the years grease has gotten into the top cap shaft throught the tiny ports at the bottom and done something? I am not really sure how to get the top cap shaft apart.

If anyone has some insight here, I'd like to hear it.

Thanks!
 

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Discussion Starter · #4 · (Edited)
maybe this will help
Thanks! I need to work on my German(?) translation, but that is super helpful.

From the diagram (1st image in the album) I am pretty sure I get how the system works, now.

I can't see anything going amiss with the DPA that would cause my end-of-travel issue.

I guess the main air chamber really is just too low volume and too progressive at the end of the stroke for me to really use the last bit of travel. Well at least I know the fork won't bottom too harshly if someone drops a piano on it.
 
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